scholarly journals Estimation of muscle activation during different walking speeds with two mathematical approaches compared to surface EMG

2018 ◽  
Vol 64 ◽  
pp. 266-273 ◽  
Author(s):  
Ursula Trinler ◽  
Fabien Leboeuf ◽  
Kristen Hollands ◽  
Richard Jones ◽  
Richard Baker
Keyword(s):  
Muscle Activation ◽  
Surface Emg ◽  
Walking Speeds

scholarly journals Antagonist Muscle Co-Activation during Kettlebell Single Arm Swing Exercise

2021 ◽  
Vol 11 (9) ◽  
pp. 4033
Author(s):  
Ahmed Salem ◽  
Amr Hassan ◽  
Markus Tilp ◽  
Abdel-Rahman Akl
Keyword(s):  
Muscle Activation ◽  
Surface Emg ◽  
Antagonist Muscle ◽  
Arm Swing ◽  
Shoulder Muscles ◽  
Antagonist Muscles ◽  
Co Activation ◽  
Integrated Emg ◽  
Post Hoc ◽  
Electrical Muscle

The purpose of this study was to determine the muscle activation and co-activation of selected muscles during the kettlebell single arm swing exercise. To the best of our knowledge, this is the first study investigating the muscle co-activation of a kettlebell single arm swing exercise. Nine volunteers participated in the present study (age: 22.6 ± 3.8 years; body mass: 80.4 ± 9.2 kg; height: 175.6 ± 7.5 cm). The electrical muscle activity of eight right agonist/antagonist muscles (AD/PD, ESL/RA, ESI/EO, and GM/RF) were recorded using a surface EMG system (Myon m320RX; Myon, Switzerland) and processed using the integrated EMG to calculate a co-activation index (CoI) for the ascending and descending phases. A significant effect of the ascending and descending phases on the muscles’ CoI was observed. Post hoc analyses showed that the co-activation was significantly higher in the descending phase compared to that in the ascending phase of AD/PD CoI (34.25 ± 18.03% and 24.75 ± 13.03%, p < 0.001), ESL/RA CoI (34.97 ± 17.86% and 24.19 ± 10.32%, p < 0.001), ESI/EO CoI (41.14 ± 10.72% and 30.87 ± 11.26%, p < 0.001), and GM/RF CoI (27.49 ± 12.97% and 34.98 ± 14.97%, p < 0.001). In conclusion, the co-activation of the shoulder muscles varies within the kettlebell single arm swing. The highest level of co-activation was observed in the descending phase of AD/PD and GM/RF CoI, and the lowest level of co-activation was observed during the descending phase, ESL/RA and ESI/EO CoI. In addition, the highest level of co-activation was observed in the ascending phase of ESL/RA and ESI/EO CoI, and the lowest level of co-activation was observed during the ascending phase, AD/PD and GM/RF CoI. The co-activation index could be a useful method for the interpretation of the shoulder and core muscles’ co-activity during a kettlebell single arm swing.

Initial phase of maximal voluntary and electrically stimulated knee extension torque development at different knee angles

2004 ◽  
Vol 97 (5) ◽  
pp. 1693-1701 ◽  
Author(s):  
C. J. de Ruiter ◽  
R. D. Kooistra ◽  
M. I. Paalman ◽  
A. de Haan
Keyword(s):  
Muscle Activation ◽  
Knee Extensor ◽  
Surface Emg ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Knee Angle ◽  
Time Integral ◽  
Voluntary Contractions ◽  
Torque Development

We investigated the capacity for torque development and muscle activation at the onset of fast voluntary isometric knee extensions at 30, 60, and 90° knee angle. Experiments were performed in subjects ( n = 7) who had high levels (>90%) of activation at the plateau of maximal voluntary contractions. During maximal electrical nerve stimulation (8 pulses at 300 Hz), the maximal rate of torque development (MRTD) and torque time integral over the first 40 ms (TTI40) changed in proportion with torque at the different knee angles (highest values at 60°). At each knee angle, voluntary MRTD and stimulated MRTD were similar ( P < 0.05), but time to voluntary MRTD was significantly longer. Voluntary TTI40 was independent ( P > 0.05) of knee angle and on average (all subjects and angles) only 40% of stimulated TTI40. However, among subjects, the averaged (across knee angles) values ranged from 10.3 ± 3.1 to 83.3 ± 3.2% and were positively related ( r2 = 0.75, P < 0.05) to the knee-extensor surface EMG at the start of torque development. It was concluded that, although all subjects had high levels of voluntary activation at the plateau of maximal voluntary contraction, among subjects and independent of knee angle, the capacity for fast muscle activation varied substantially. Moreover, in all subjects, torque developed considerably faster during maximal electrical stimulation than during maximal voluntary effort. At different knee angles, stimulated MRTD and TTI40 changed in proportion with stimulated torque, but voluntary MRTD and TTI40 changed less than maximal voluntary torque.

scholarly journals Active Passive Nature of Assistive Wearable Gait Augment Suit for Enhanced Mobility

2018 ◽  
Vol 30 (5) ◽  
pp. 717-728 ◽  
Author(s):  
Chetan Thakur ◽  
Kazunori Ogawa ◽  
Yuichi Kurita ◽  
◽  
◽  
...  
Keyword(s):  
Lower Limb ◽  
Muscle Activation ◽  
Feedforward Control ◽  
Surface Emg ◽  
Walking Gait ◽  
Lower Limb Muscles ◽  
Air Supply ◽  
Pilot Trials ◽  
Pneumatic Valves ◽  
Enhanced Mobility

In this paper we discuss the active and passive nature of the assistive wearable gait augment suit (AWGAS). AWGAS is a soft, wearable, lightweight, and assists walking gait by reducing muscle activation during walking. It augments walking by reducing the muscle activation of the posterior and anterior muscles of the lower limb. The suit uses pneumatic gel muscles (PGM), foot sensors for gait detection, and pneumatic valves to control the air pressure. The assistive force is provided using the motion in loop feedforward control loop using foot sensors in shoes. PGMs are actuated with the help of pneumatic valves and portable air tanks. The elastic nature of the PGM allows AWGAS to assist walking in the absence of the air supply which makes AWGAS both active and passive walking assist suit. To evaluate the active and passive nature of the AWGAS, we experimented to measure surface EMG (sEMG) of the lower limb muscles. sEMG was recorded for unassisted walking, i.e., without the suit, passive assisted walking, i.e., wearing the suit with no air supply and active assisted walking, i.e., wearing the suit with air supply set at 60 kPa. The results shows reduction in the muscle activity for both passive and active assisted walking as compared to unassisted walking. The pilot trials of the AWGAS were conducted in collaboration with local farmers in the Hiroshima prefecture in Japan where feedback received is complementing the results obtained during the experiments.

Intent-Related Differences in Surface EMG of Maximum Eccentric and Concentric Contractions

2003 ◽  
Vol 19 (2) ◽  
pp. 99-105 ◽  
Author(s):  
Mark D. Grabiner ◽  
Tammy M. Owings
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Eccentric Contraction ◽  
Surface Emg ◽  
Vastus Lateralis Muscle ◽  
Concentric Contractions ◽  
Concentric Contraction ◽  
Contraction Condition ◽  
The Difference

For this study it was hypothesized that when participants intended to perform a maximum voluntary concentric (or eccentric) contraction but had an eccentric (or concentric) contraction imposed upon them, the initial EMG measured during the isometric phase preceding the onset of the dynamometer motion would reflect the intended contraction condition. The surface EMG of the vastus lateralis muscle was measured in 24 participants performing isokinetic concentric and eccentric maximum voluntary knee extensor contractions. The contractions were initiated from rest and from the same knee flexion angle and required the same level of external force to trigger the onset of dynamometer motion. Vastus lateralis EMG were quantified during the isometric phase preceding the onset of the dynamometer motion. When participants intended to perform a concentric contraction but had an eccentric contraction imposed upon them, the initial EMG resembled that of a concentric contraction. When they intended to perform an eccentric contraction but had a concentric contraction imposed upon them, the initial EMG resembled that of an eccentric contraction. Overall, the difference between concentric and eccentric contractions observed during the period of theinitialmuscle activation implies that descending signals include information that distinguishes between eccentric and concentric contractions.

scholarly journals HDsEMG Activity of the Lumbar Erector Spinae in Violin Players: Comparison of Two Chairs

2019 ◽  
Vol 34 (4) ◽  
pp. 205-214 ◽  
Author(s):  
Alessandro Russo ◽  
Alejandra Aranceta-Garza ◽  
Samuel D’Emanuele ◽  
Francesca Serafino ◽  
Roberto Merletti
Keyword(s):  
Muscle Activation ◽  
Surface Emg ◽  
Erector Spinae ◽  
Mean Square ◽  
Electrode Arrays ◽  
Spatial And Temporal Patterns ◽  
Rates Of Change ◽  
Density Surface ◽  
The Mean ◽  
Spectral Frequency

This study compared an ergonomic alternative chair (A-chair) with a standard orchestra chair (O-chair) used by a group of 9 violin players. The features of the high-density surface EMG (HDsEMG) of the lumbar erector spinae muscles were used for the comparison. The violinists played the same pieces of music for 2 hrs without interruption on each chair in 2 different days, 1 week apart. HDsEMG was recorded for 20 s every 5 minutes using two electrode arrays of 16 × 8 electrodes each, one on each side of the spine and placed between the T11 and L4 levels. The sEMG was non-stationary and burst-like patterns were observed on 8 out of 9 violinists. The mean root mean square (RMS) and mean spectral frequency (MNF) value over the region of activity (ROA), the centroid of the ROA, the rates of change in time of the spatial mean of the RMS and MNF values, and the burst frequencies associated with the two chairs were compared. Statistically significant reductions of RMS were observed in each violinist between the O-chair and A-chair (range 11.80−78.36%). No significant changes of other spatial or spectral sEMG features were globally observed versus time or between chairs but were demonstrated by some subjects. It is concluded that the A-chair is associated with a decrease of the sEMG amplitude of the ESM without changes of the spatial and temporal patterns of muscle activation.

scholarly journals Electromyographic measures of muscle activation and changes in muscle architecture of human elbow flexors during fatiguing contractions

2008 ◽  
Vol 104 (6) ◽  
pp. 1720-1726 ◽  
Author(s):  
Thorsten Rudroff ◽  
Didier Staudenmann ◽  
Roger M. Enoka
Keyword(s):  
Muscle Activation ◽  
Biceps Brachii ◽  
Surface Emg ◽  
Muscle Architecture ◽  
Surface Measurement ◽  
Emg Activity ◽  
Time To Failure ◽  
Elbow Flexors ◽  
Emg Amplitude ◽  
Rate Of Increase

The study compared changes in intramuscular and surface recordings of EMG amplitude with ultrasound measures of muscle architecture of the elbow flexors during a submaximal isometric contraction. Ten subjects performed a fatiguing contraction to task failure at 20% of maximal voluntary contraction force. EMG activity was recorded in biceps brachii, brachialis, and brachioradialis muscles using intramuscular and surface electrodes. The rates of increase in the amplitude of the surface EMG for the long and short heads of biceps brachii and brachioradialis were greater than those for the intramuscular recordings measured at different depths. The amplitude of the intramuscular recordings from three muscles increased at a similar rate ( P = 0.13), as did the amplitude of the three surface recordings from two muscles ( P = 0.83). The increases in brachialis thickness (27.7 ± 5.7 to 30.9 ± 3.5 mm; P < 0.05) and pennation angle (10.9 ± 3.5 to 16.5 ± 4.8°; P = 0.003) were not associated with the increase in intramuscular EMG amplitude ( P > 0.58). The increase in brachioradialis thickness (22.8 ± 4.8 to 25.5 ± 3.4 mm; P = 0.0075) was associated with the increase in the amplitude for one of two intramuscular EMG signals ( P = 0.007, r = 0.79). The time to failure was more strongly associated with the rate of increase in the amplitude of the surface EMG than that for the intramuscular EMG, which suggests that the surface measurement provides a more appropriate measure of the change in muscle activation during a fatiguing contraction.

scholarly journals Concurrent surface electromyography and force myography classification during times of prosthetic socket shift and user fatigue

2017 ◽  
Vol 4 ◽  
pp. 205566831770873 ◽  
Author(s):  
Joe Sanford ◽  
Rita Patterson ◽  
Dan O Popa
Keyword(s):  
Surface Electromyography ◽  
Muscle Activation ◽  
Surface Emg ◽  
Training Data ◽  
Control Input ◽  
Prosthetic Devices ◽  
Prosthetic Socket ◽  
User Fatigue ◽  
Force Myography

Objective Surface electromyography has been a long-standing source of signals for control of powered prosthetic devices. By contrast, force myography is a more recent alternative to surface electromyography that has the potential to enhance reliability and avoid operational challenges of surface electromyography during use. In this paper, we report on experiments conducted to assess improvements in classification of surface electromyography signals through the addition of collocated force myography consisting of piezo-resistive sensors. Methods Force sensors detect intrasocket pressure changes upon muscle activation due to changes in muscle volume during activities of daily living. A heterogeneous sensor configuration with four surface electromyography–force myography pairs was investigated as a control input for a powered upper limb prosthetic. Training of two different multilevel neural perceptron networks was employed during classification and trained on data gathered during experiments simulating socket shift and muscle fatigue. Results Results indicate that intrasocket pressure data used in conjunction with surface EMG data can improve classification of human intent and control of a powered prosthetic device compared to traditional, surface electromyography only systems. Significance Additional sensors lead to significantly better signal classification during times of user fatigue, poor socket fit, as well as radial and ulnar wrist deviation. Results from experimentally obtained training data sets are presented.

Motor unit firing rates during isometric voluntary contractions performed at different muscle lengths

2004 ◽  
Vol 82 (8-9) ◽  
pp. 769-776 ◽  
Author(s):  
Alejandro Del Valle ◽  
Christine K Thomas
Keyword(s):  
Motor Unit ◽  
Muscle Activation ◽  
Muscle Length ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Force Frequency ◽  
Triceps Brachii ◽  
Firing Rates ◽  
Motor Unit Firing ◽  
Voluntary Contractions

Firing rates of motor units and surface EMG were measured from the triceps brachii muscles of able-bodied subjects during brief submaximal and maximal isometric voluntary contractions made at 5 elbow joint angles that covered the entire physiological range of muscle lengths. Muscle activation at the longest, midlength, and shortest muscle lengths, measured by twitch occlusion, averaged 98%, 97%, and 93% respectively, with each subject able to achieve complete activation during some contractions. As expected, the strongest contractions were recorded at 90° of elbow flexion. Mean motor unit firing rates and surface EMG increased with contraction intensity at each muscle length. For any given absolute contraction intensity, motor unit firing rates varied when muscle length was changed. However, mean motor unit firing rates were independent of muscle length when contractions were compared with the intensity of the maximal voluntary contraction (MVC) achieved at each joint angle.Key words: muscle activation, length–tension relationships, force–frequency relationships.

scholarly journals The Electromyographic Threshold in Girls and Women

2017 ◽  
Vol 29 (1) ◽  
pp. 84-93 ◽  
Author(s):  
Devon Long ◽  
Raffy Dotan ◽  
Brynlynn Pitt ◽  
Brandon McKinlay ◽  
Thomas D. O’Brien ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Regression Line ◽  
Surface Emg ◽  
Cycle Ergometry ◽  
High Threshold ◽  
Type Ii ◽  
Progressive Exercise ◽  
Muscular Function ◽  
The Right

Background:The electromyographic threshold (EMGTh) is thought to reflect increased high-threshold/type-II motor-unit (MU) recruitment and was shown higher in boys than in men. Women differ from men in muscular function.Purpose:Establish whether females’ EMGTh and girls–women differences are different than males’.Methods:Nineteen women (22.9 ± 3.3yrs) and 20 girls (10.3 ± 1.1yrs) had surface EMG recorded from the right and left vastus lateralis muscles during ramped cycle-ergometry to exhaustion. EMG root-mean-squares were averaged per pedal revolution. EMGTh was determined as the least residual sum of squares for any two regression-line data divisions, if the trace rose ≥ 3SD above its regression line. EMGTh was expressed as % final power-output (%Pmax) and %VO2pk power (%PVO2pk).Results:EMGTh was detected in 13 (68%) of women, but only 9 (45%) of girls (p < .005) and tended to be higher in the girls (%Pmax= 88.6 ± 7.0 vs. 83.0 ± 6.9%, p = .080; %PVO2pk= (101.6 ± 17.6 vs. 90.6 ± 7.8%, p = .063). When EMGTh was undetected it was assumed to occur at 100%Pmax or beyond. Consequently, EMGTh values turned significantly higher in girls than in women (94.8 ± 7.4 vs. 88.4 ± 9.9%Pmax, p = .026; and 103.2 ± 11.7 vs. 95.2 ± 9.9%PVO2pk, p = .028).Conclusions:During progressive exercise, girls appear to rely less on higher-threshold/type-II MUs than do women, suggesting differential muscle activation strategy.

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